Some known thermal energy storage systems may store thermal energy in the form of ice and/or heat and, at some later time, may use the stored thermal energy to make electrical power. Some known types of thermal energy storage systems may incur inefficiencies because they use electricity to make ice. As a result, inefficiencies inherent therein may be incurred twice. Also, some known types of thermal energy storage systems may use one machine to buy electricity to charge hot and cold thermal heat sources (such as via a heat pump), then wait for some period of time before using another system to discharge the thermal energy storage tanks to make power. Moreover, in some known types of thermal energy storage systems, working fluid may flow in more than one direction and/or at more than one mass flow rate in components of the thermal energy storage system in different modes of operation.